This invention relates to document feeders and more particularly to an envelope feeder used to transport documents from an envelope tray or hopper to a document reading location. The document is then read by an operator and upon command is released from the feeder and transported to envelope receiving bins.
There are many examples of times and places where envelopes are transported from a stack to an envelope reading station or to envelope processing equipment. Heretofore, the envelopes have often been withdrawn from the stack by a document feeder, deposited onto a transport mechanism, and transported to the document reading station. The document transport stops the document at the reading station where it is read by an operator and the operator performs a function in response to reading the envelope. For example, the envelopes can be pre-addressed and are transported to a reading station where the operator reads the zip code and keys it into a computer by means of a keyboard. The operator then advances the envelope to a bar-code printing station wherein a bar-code is printed on the envelope which corresponds to the zip code entered by the operator. It is apparent that there is a need to simplify the transporting of the envelopes from the hopper to the printer.
Applicant's invention provides a document feeder which employs a pair of drive rollers mounted on a first drive shaft. These rollers are rotated in a forwardly driving direction and mounted to the drive shaft by means of a one-way clutch which allows the drive rollers to rotate only in the forwardly driving direction.
Mounted below the drive rollers are a pair of driven rollers. The driven rollers rotate in an envelope feeding direction when an envelope is in the nip defined between the drive and driven rollers. The force of the driving roller is transmitted through the document to the driven roller causing the driven roller to rotate in the document feed direction. A relatively constant braking force is applied by braking means to the driven rollers to provide a relatively constant force counter to the force transmitted through the envelope. The braking force minimizes the possibility of two documents being fed through the nip at the same time by stopping the second envelope until the first envelope clears the nip. A second set of drive and driven rollers are positioned downstream of the first set to give added security of feeding only one envelope at a time and to hold the envelope with a portion of it extending into the reading area.
The drive rollers are connected to and driven by a reversible motor. Positioned between the two sets of rollers is a photo-electric sensor which signals a controller when the trailing edge of a document enters the second set or downstream set of rollers. The sensor gives a signal to the controller which stops and reverses the motor. The envelope does not move any substantial amount in the downstream direction after the trailing edge of the envelope passes the photo-electric sensor. The one-way clutches permit the shafts upon which the drive rollers are mounted to rotate in a direction counter to the feeding direction without causing the drive rollers to also rotate in the reverse feed direction. The brake means on the driven rollers stop the envelope against the drive roller with the trailing edge of the envelope retained in the nip. In this postion the address or zip code on the envelope can be read by an operator. Responsive to the operator's signal, the drive system is energized to release the envelope and transport the next following envelope through the rollers wherein the cycle is repeated. The envelopes are dropped from the second set of rollers onto an envelope transport and can be further processed.
Accordingly, an object of the invention is to provide an envelope feeding device that simply and efficiently transports envelopes from a hopper to a document reading area where the envelope is read, and upon command of the operator transported to further envelope processing means. Related to this is the object of feeding envelopes to the reading area and precisely stopping each envelope at a predetermined point.
Another object of the invention is to provide an envelope feeder which automatically compensates for various thicknesses and sizes of envelopes.
Still another object of the invention is to provide an envelope feeder which has means to separate envelopes and avoid two envelopes being simultaneously fed.
Many other objects and purposes of the invention will be clear from the following description of the drawings.